This invention relates to a tubular medical device designed for insertion into a body, for example a hollow organ or body cavity (heart, blood vessel, alimentary canal, urethra, abdominal cavity, etc.), for medical examination or treatment, and especially to a tubular medical device used for guiding an endoscope into a hollow organ or body cavity to examine.
Low invasive operations are gradually taking the place of high invasive operations such as incision. Especially, application of endoscopic surgery using an endoscope has rapidly spread in recent year.
Endoscopic surgery was generally in the field of digestive organs. It was then applied to the field of respiratory organ, ear/nose/throat, neurosurgery, obsterics and gynecology, and orthopedics.
A small-diameter endoscope system used for endoscopic surgery comprises a catheter body which is inserted into the body of a patient and a control portion which an operator manipulates by hands. The catheter body is generally provided at the distal end portion with a mechanism which turns the distal end portion in an intended direction in order to make the distal end portion proceed along a curved or branched hollow organ (insertion path) or to view a different part of the organ.
To make the distal end portion of a tubular medical device bendable, a method which connects two or more articulation rings movably in series and bends the distal end by pulling a wire (wires) is used. However, a tubular medical device which does not have articulation rings is proposed to meet the increasing request for a thinner endoscope.
The tubular medical device has a closely wound coil with a compression resistance in the direction of the axis securely held in a lumen extending throughout the entire length of the tubular body except the distal end portion. This tubular medical device has a wire whose distal end is secured near the distal end of the tubular body away from the axis and which is passed through the compression-resisting member or another lumen The distal end portion of this tubular medical device can be bent from outside the body by pulling the proximal end of the wire Japanese Patent Application laid open under No. 94-343702). This tubular medical device is made so that only the distal end portion bends to pull on the wire, by putting a closely wound coil in the tubular body which resists compression in the direction of the axis.
In the manufacturing process of this tubular medical device, a lumen in which the closely wound coil is held is formed in the tubular body, then the closely wound coil is inserted into the lumen to the predetermined position, and the coil is secured in the lumen at some portions (distal end portions and proximal end portion of the coil, for example). To make insertion of the coil into the lumen in this process, the interior diameter of the lumen must be made a little larger than the exterior diameter of the coil, and hence a certain gap is inevitably formed between the inside wall of the lumen and the outside surface of the coil. Because of its very small exterior diameter of the coil and a gap between the inside wall of the lumen and the outside surface of the coil, the coil easily bends in the lumen to a small compressing force except the secured portions.
If the wire is pulled when the coil is thus bending, the pulling force is applied in a direction deviated from the direction axis, the coil bends easily. As the result, not only the distal end portion of the tubular body but also the portion with the coil put in bends, and hence the distal end portion does not bend accurately according to pull on the wire.
The object of this invention is to solve the above problem, by providing an improved tubular medical device for insertion into a body only the distal end portion of which bends accurately according to the pulling force.
This object is attained by the tubular medical device of this invention which comprises a tubular body, a lumen extending in almost entire length of said tubular body, and a compression-resisting member which is held in said lumen with a distal end positioned at a predetermined distance from a distal end of said tubular body to a proximal side and secured in said lumen so as not to move in a direction of an axis of said tubular body, a wire whose distal end is secured at a position in a wall of said tubular body close to said distal end of said tubular body and displaced from the axis of said tubular body and whose a proximal end is lead out of a proximal end of said tubular body, means for pulling said wire which is provided at the proximal side of said tubular body and operated to control a direction of a distal end portion of said tubular body by said wire. The said compression-resisting member comprises a major component which constitutes an essential part of said compression-resisting member and resists a pressure in a direction of a length and secured portions which are connected to said major component or formed as integrated parts of said major component.